Electrodeposition has gained popularity in the coatings industry because it can often provide higher paint utilization, outstanding corrosion resistance, and/or low environmental contamination as compared with non-electrophoretic coating methods. Both cationic and anionic electrodeposition are used commercially, with cationic often being more prevalent in applications desiring a high level of corrosion protection. Anionic electrodeposition is often used for decorative applications, particularly where low cost and decorative qualities are desired.
There are a number of applications in which it is desired to control the gloss of a coating layer applied by electrodeposition. Electrodepositable coating compositions having high gloss levels are readily achievable, but compositions with low gloss levels while maintaining acceptable smoothness of the cured film have been very difficult to achieve.
Traditional flatting agents used to reduce gloss in electrodepositable coating compositions typically include inorganic pigments and fillers, such as silicas, clays and/or talcs. While these materials are often effective in reducing gloss to a certain level, the amount of these materials often required to achieve a low gloss film not only may adversely impact the coating viscosity, but also the smoothness of the resultant cured film. It would therefore be desirable to have a method for making an electrodepositable coating composition that achieves a low gloss while maintaining acceptable smoothness of the cured film.
The present invention has been developed in view of the foregoing.